Device of flashing incandescent lamp with heat sensitive element for shunting a portion of the incandescent filament



Feb. 25, 1964 E LONN ETAL 3,122,675

DEVICE 0F FLASHING INCANDESCENT LAMP WITH HEAT SENSITIVE ELEMENT FOR SI-IUNTING A PORTION OF THE INCANDESCENT FILAMENT Original Filed June 6, 1955 I 3 Sheets-Sheet 1 Fig.1a

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DEVICE OF FLASHING INCANDESCENT LAMP WITH HEAT SENSITIVE ELEMENT FOR SHUNTING A PORTION OF THE INCANDESCENT FILAMENT Original Filed June-6, 1955 5 Sheets-Sheet 2 F ig. 2a

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DEVICE 0F FLASHING INCANDESCENT LAMP WITH HEAT SENSITIVE ELEMENT FOR SHUNTING A PORTION OF THE INCANDESCENT FILAMENT Original Filed June 6, 1955 3 Sheets-$heet 3 Fig.3a

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H i i H, il 2 9 l iw efl United States Patent Ofitice 3,122,675 Patented Feb. 25, 1964 DEVICE OF FLASHING INCANDESCENT LAMP WITH HEAT SENSITIVE ELEMENT FOR SHUNT- ING A PORTION OF THE INCANDESCENT FILAMENT Erik Ivan Lorin, Johanneshov, and Selfrid Gunnar Ohlund, Hagersten, Sweden, assignors to Lumalampan Aktieholag, Stockholm, Sweden, a corporation of Sweden Continuation of application Ser. No. 513,432, June 6,

1955. This application Apr. 19, 1962, 591'. No. 193,642.

Claims priority, application Sweden June 12, 1954 6 Claims. (Cl. 315-73) This invention relates to a device of incandescent electric lamps causing the light to twinkle. This application is a continuation of our co-pending application S.N. 513,432, filed June 6, 1955 and now abandoned.

Incandescent electric lamps emitting twinkling light are sometimes wanted, as for instance, for motor-car blinkers and for Christmas tree and display illumination sets, with the aim to imitate candle-light. In installations of the latter kind, each lamp should twinkle independently of the others. It is further desired that in twinkling the brightness of each lamp should vary between different limits without extinguishing the lamp.

It is already known, for instance by the Swedish Patent No. 140,919, how periodical short-circuiting or by-passing of a section of a lamp filament can be rovided for by a bimetal spring heated by said section. In these known arrangements the bimetal spring forms part of the current circuit of the filament, being one of its points or" support. Therefore, the filament takes part in the periodical movements of the bimetal spring, resulting in a certain bending of the filament, reducing its burning life.

The present invention eliminates this disadvantage by providing for at least three points of support at both ends and at least one more at an intermediate point of the filament. The bimetal spring is fixed to one of these points of support in such a way as to make contact with an adjacent point of support, when heated by the fila ment section between both points.

The invention will now be described with reference to the accompanying drawings, FIGS. 1a, 2a, and 3a showing the front elevations of three different embodiments of the invention, FIGS. lb, 2b, and 3b showing their side elevations.

1 in the figures shows a lamp bulb with a cap 2; 3 and 4 are the two leading-in wires for the filament, which consists of two parts, 5 and 6. The leading-in wires 3 and 4 are sealed in a glass support body 7, and 8 is a so-called by-pass, for instance a strip of oxidized aluminum sheet bent around both leading-in wires, shortcircuiting them in case of filament failure and securing that in case of many lamps in series, failure of one lamp would not cut out all the others.

The arrangement in FIGS. 1a and 1b shows a filament, 5 and 6, bent into V-shape and supported at its vertex by an elastic support wire 9. A single bimetal spring is fixed to the support wire so as to bisect the angle between the limbs 5 and 6. When the lamp is on, the bimetal spring 10 is heated and bends itself, for instance to the left (FIG. 1a), making contact with the end of the leading-in wire 3, thereby short-circuiting section 5 of the filament, which reduces its radiation of heat to the bimetal spring. The bimetal spring then withdraws from the leading-in wire 3, thereby causing section 5 of the filament to reglow and the process to repeat itself.

The arrangement in FIGS. 2a and 2b has also an elastic support wire 9 supporting a V-shaped filament in its vertex. A bimetal spring consisting of two almost parallel strips, 11 and 12, is fixed to support wire 9. When the lamp is on, the bimetal spring, 11 and 12, is heated, causing strip 11 to bend to the left and strip 12 to the right and bringing the strips into contact with the leading-in wires 3 and 4, one prior to the other. Consequently, half of the filament is short-circuited, whereupon the other half becomes extinguished. Then one half of the filament is lit and after a While also the other one, whereupon the process repeats itself. The brightness of such a lamp changes between three different values. With diiferent lenghts for the two sections of the filament four different values of brightness are provided for viz.:

(a) With the whole of the filament aglow,

(b) With one section of the filament aglow,

(0) With the other section aglow, and

(d) With the whole of the filament extinguished.

The filament can also be provided with a third section, not being short-circuited. That results in that the brightness is replaced by a brightness corresponding to the brightness of the third section.

In the embodiment according to FIGS. 3a and 3b the filament is approximately straight and stretched between the leading-in wires, of which No. 3 is prolonged to extend through the lamp. An extra support wire 13 is attached to the glass body 7 to support the filament in the middle. A bimetal spring 14 is attached to the leadingin wire 3 being bent to be approximately parallel to section 5 of the filament, though some distance off. When the lamp is lit this bimetal spring is heated, whereupon it bends its free end towards the support wire 13, short-circuiting section 5 of the filament. The bimetal spring cools therewith and returns to its initial position, whereupon the process is repeated.

The embodiment shown in FIG. 3 is particularly favorable, being simple to manufacture and very stable and durable. It provides many possibilities of adapting the brightness of section 5 of the filament, which is to be short-circuited by the bimetal spring, to the brightness of section 6 of the filament, so that suitable intensity variations in twinkling may be obtained. The bimetal strip is designed so that, after the lamp has been mounted and exhaustedtherewith being heated to for example 360 C. to 500 C.the bimetal spring by the heating has been caused to change its position, so that it rests against the lamp bulb in the cooled down lamp. With the lamp at the normal operating temperature, the bimetal strip has then a position suitable for the twinkling frequency, enabling the radiant heat from the section of the filament that is to be switched oil to achieve the short-circuiting.

In addition to the special embodiments of the inven tion described above, a variety of arrangements may fall under the claims of this application.

What is claimed is:

1. In an electric lamp adapted to flicker rapidly and automatically between a full intensity of light and a diminished intensity and having a hollow Lamp bulb enclosing a filamentasupporting stem therein, the combination which comprises an elongated light producing filarnent, end support means on said stem for supporting each opposite end of said filament to a fixed position within said bulb, said end support means also providing means for conducting electric current to and through said filament, additional intermediate support means on said stern for supporting said filament intermediate said opposite ends thereof and defining two generally vertical portions or said filament, said intermediate support means also providing electrical contact with said filament, an elongated flat heat-sensitive and electrically conductive strip element adapted to flex in response to variations in temperature, said strip element being afiixed to one of said support means and extending adjacent another of said support means for establishing electrical contact between one of said end support means and said intermediate support means upon heating said strip element effecting an electrical shunt therebetween tie-energizing one of said two portions of saidfilament, and said strip element being disposed closely adjacent and substantially coextensively aligned with said one portion of said filament with a flat side of said strip facing said portion of said filament in direct l1eatreceiving relation thereto.

2. In an electric lamp adapted to flicker rapidly and automatically between a full intensity of light and a diminished intensity and having a hollow lamp bulb enclosing a filament-supporting stern therein, the combination which comprises an elongated light-producing filament, end support means on said stem for supporting each opposite end of said filament in a fixed position within said bulb, said end support means also providing means for conducting electric current to and through said filament, additional intermediate support means on said stern for supporting said filament intermediate said opposite ends thereof and defining two generally vertical portions of said filament, said intermediate support means also providing electrical contact with said filament, an elongated flat bimetallic heat-sensitive and electrically conductive strip element adapted to fiex in response to variations in temperature, said strip element being atfixed at one end to one of said end support means and extending adjacent said intermediate support means for flexing movement from a lower temperature open position to a higher temperature closed position in which said strip element contacts said intermediate support means effecting an electrical shunt therewith de-energizing one of said two portions of said filament upon heating of said strip element, and said strip element being disposed closely adjacent and substantially co-extensively aligned with said one portion of said filament with a flat side of said strip element facing said portion of said filament in direct heat-receivin g relation thereto.

3. An electric lamp as recited in claim 2 in which said strip element is also disposed relative to said lamp bulb whereby said strip element in said lower temperature open position thereof is in contact with said bulb.

4. An electric lamp as recited in claim 2 in which both said portions of said elongated filament are substantially vertically aligned within said bulb and in which one of 4 said portions on one side of said inte mediate support means is longer than the other said portion of said filament.

5. In an electric lamp adapted to flicker rapidly and automatically between a full intensity of light and a diminished intensity and having a hollow lamp bulb enclosing a filament-supporting stem therein, the combination which comprises an elongated light-producing filament, end support means on said stem for supporting each opposite end of said filament in a fixed position within said bulb, said end support means also providing means for conducting electric current to and through said filament, additional intermediate support means on said stem for supporting said filament intermediate said opposite ends thereof and in a generally V-shaped configuration defining two generally vertical portions of said filament, said intermediate support means also providing electrical contact with said filament, an elongated fiat bimetallic heatsensitive and electrically conductive strip element adapted to flex in response to variations in temperature, said strip element being affixed at one end to said intermediate support means for temperature-induced flexing from an open position to a closed position in which said strip element contacts one of said end support means forming an electrical shunt between said intermediate support and said end support de-energizing one of said two portions of said filament, and said strip element being disposed vertically between said two portions of said filament and substantially co-extensively aligned therewith with a fiat side of said strip element facing said portion of said filament in direct heat-receiving relation thereto. r

6. An electric lamp as recited in claim 5 which also includes a second fiat bimetallic strip element also affixed to said intermediate support means for temperature-induced flexing with respect to the other of said end support means intermittently forming therewith an electrical shunt die-energizing the other of said two portions of said filament, and in which said two strip elements ficx with different time periods for separately de-energizing said two portions of said filament with diiferent frequencies.

References Cited in the file of this patent UNITED STATES PATENTS 2,235,360 Davis Mar. 18, 1941 2,361,485 MacGregor Oct. 31, 1944 2,627,590 Ohlund Feb. 3, 1953 

1. IN AN ELECTRIC LAMP ADAPTED TO FLICKER RAPIDLY AND AUTOMATICALLY BETWEEN A FULL INTENSITY OF LIGHT AND A DIMINISHED INTENSITY AND HAVING A HOLLOW LAMP BULB ENCLOSING A FILAMENT-SUPPORTING STEM THEREIN, THE COMBINATION WHICH COMPRISES AN ELONGATED LIGHT-PRODUCING FILAMENT, END SUPPORT MEANS ON SAID STEM FOR SUPPORTING EACH OPPOSITE END OF SAID FILAMENT TO A FIXED POSITION WITHIN SAID BULB, SAID END SUPPORT MEANS ALSO PROVIDING MEANS FOR CONDUCTING ELECTRIC CURRENT TO AND THROUGH SAID FILAMENT, ADDITIONAL INTERMEDIATE SUPPORT MEANS ON SAID STEM FOR SUPPORTING SAID FILAMENT INTERMEDIATE SAID OPPOSITE ENDS THEREOF AND DEFINING TWO GENERALLY VERTICAL PORTIONS OF SAID FILAMENT, SAID INTERMEDIATE SUPPORT MEANS ALSO PROVIDING ELECTRICAL CONTACT WITH SAID FILAMENT, AN ELONGATED FLAT HEAT-SENSITIVE AND ELECTRICALLY CONDUCTIVE STRIP ELEMENT ADAPTED TO FLEX IN RESPONSE TO VARIATIONS IN TEMPERATURE, SAID STRIP ELEMENT BEING AFFIXED TO ONE OF SAID SUPPORT MEANS AND EXTENDING ADJACENT ANOTHER OF SAID SUPPORT MEANS FOR ESTABLISHING ELECTRICAL CONTACT BETWEEN ONE OF SAID END SUPPORT MEANS AND SAID INTERMEDIATE SUPPORT MEANS UPON HEATING SAID STRIP ELEMENT EFFECTING AN ELECTRICAL SHUNT THEREBETWEEN DE-ENERGIZING ONE OF SAID TWO PORTIONS OF SAID FILAMENT, AND SAID STRIP ELEMENT BEING DISPOSED CLOSELY ADJACENT AND SUBSTANTIALLY COEXTENSIVELY ALIGNED WITH SAID ONE PORTION OF SAID FILAMENT WITH A FLAT SIDE OF SAID STRIP FACING SAID PORTION OF SAID FILAMENT IN DIRECT HEAT-RECEIVING RELATION THERETO. 